Time-delay devices



NOV. 15, 1960 PETRIE 2,960,638

TIME-DELAY DEVICES Filed April 10. 1957 F l G. I

INVENTOR. EDGAR H. PETRIE ATTORNEY.

United States Patent TIME-DELAY DEVICES Edgar H. Petrie, Levittown, Pa., assignor to Minneapolis- Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Filed Apr. 10, 1957, Ser. No. 652,035

1 Claim. (Cl. 317-155.5)

This invention relates to relays, and more particularly to time-delay relays.

Frequently, in the art of industrial or process controls, it is desirable to provide means whereby one phase of a control system may be actuated a measured or predetermined time after the occurrence of some other phase of the system control. It is also desirable to have such means conveniently variable to introduce variable time elements under various process conditions. Heretofore, various types of time-delay devices, have been provided. However, these were not entirely satisfactory in that they were excessively expensive, were not sufliciently reliable, or were not sufliciently flexible in their operation, i.e., the time element could not be conveniently varied.

It is, accordingly, an object of this invention to provide an improved time-delay device.

It is another object of this invention to provide an improved time'delay relay which features a readily available variable time-delay means.

It is a further object of this invention to provide an improved time-delay relay as set forth which is simple in structure and operation, and which is reliable in service.

In accomplishing these and other objects, there has been provided, in accordance with the present invention, an improved device in which an iron core is moved by the condition of energization of a surrounding coil in accordance with the principles of the solenoid. However, the motion of the core member is impeded by the passage of a viscous fluid through an orifice in a member attached to the core. The viscosity of the fluid is rendered variable, under the control of an external influence, to correspondingly vary the time-delay aspect of the operation of the apparatus.

A better understanding of this invention may be had from the following detailed description when read in conjunction with the accompanying drawing in which:

Fig. 1 is a schematic representation of one form of structure embodying the present invention;

Fig. 2 is a schematic representation, in an elevational view, of a different form of structure also embodying the present invention; and

Fig. 3 is a top view of the structure shown in Fig. 2.

Referring now to the drawing in more detail, there is shown in Fig. l a time-delay relay which includes the main housing element 2 at least the upper portion of which may suitably be made of a non-conductive material. In the housing element 2 there is supported an iron core element 4. Depending from the iron core 4, there is a non-magnetic cylinder 6 with an orifice 8 in the lower end thereof. In the lower end of the housing 2 there is a reservoir containing a supply of a viscous fluid 10 which may suitably be an oil having suspended therein finely divided iron particles. In the upper portion of the housing member 2 there is positioned a return spring 12, one end of which is secured to the housing 2, the other end being secured to a boss or stud 14 which extends upwardly from the iron core 4. Connected to the boss or stud 14 there is a pair of switch plate elements 16 and 18, respectively. Projecting through the housing 2 is a first pair of electrical contacts 20 and 22, respectively, positioned to be engaged by the element 16, as set forth more fully hereinbelow. A second pair of electrical contacts 24 and 26 are similarly positioned, projecting through the housing 2, and arranged to be engaged by the element 18. Suitable stops 28 are provided, projecting inwardly from the housing member 2 to limit the upward motion of the core member 4 by engagement with the upper surface of the element 18. Surrounding the middle portion of the housing 2, there is positioned an electrical field-coil or solenoid winding 30 which may be energized by electrical signals applied thereto over a pair of leads 32. Surrounding the lower end of the housing 2, there is a second field-coil 34 which may be energized by electrical signals applied thereto over a pair of leads 36.

The viscous fluid 10 in the lower end of the housing 2 is of the type of material the viscosity of which may be varied in accordance with an applied magnetic field. In this case, the magnetic field is supplied by the coil 34. Connected to the leads 36 there may be provided an adjustable source of electrical energy represented by the battery 38, across which is connected a slidewire resistor 40 and an adjustable tap or slider 42. The slidewire may be calibrated in terms of time-delay as, for example, by an adjacent scale 44. For any given setting of the movable tap 4-2 on the slidewire 40 the magnetic field produced by the coil 34 results in a predetermined viscosity of the fluid 10.

When a control signal is applied to the leads 32, energizing the coil 30, the resultant field tends to move the iron core 4 downward in the housing 2. However, the downward movement of the core 4 is impeded by the fluid 10. The rapidity of the response, in motion, of the core 4 depends upon the rate of the passage of the fluid 10 through the orifice 8 in the lower end of the cylindrical member 6. The rapidity of the passage of the fluid 10 through the orifice 8 is, in turn, a function of the viscosity of the fluid and the dimensions of the orifice. Since the dimensions of the orifice are fixed, the viscosity of the fluid will be the determining factor in the time required for the fluid to pass therethrough. For any given setting of the slider 42 on the slidewire 40, there will be produced a predetermined magnetic field by the coil 34 which, in turn, produces a predetermined viscosity in the fluid 10. Under normal condition, the iron core 4 is held in its upper limit of movement by the spring 12. In this position there may be provided, as shown, a pair of contacts 20 and 22 which are engageable and interconnected by the switch element 16. This arrangement may close a circuit which is to be operative during the quiescent stages of the operation of the herein disclosed apparatus. When a signal is applied to the leads 32, and thereby to the coil 30, the core, as previously mentioned, is urged downward. After a period of time determined by the delay introduced as a result of the passage of the fluid 10 through the orifice 8, the core assembly will have moved downward sufliciently to permit the switch element 18 to engage and interconnect the second pair of contact elements 24 and 26. These contacts may be connected to circuit elements which are to be activated a predetermined time following the occurrence of the event which caused the energization of the coil 36. It may be seen that if a different time-delay is desired, a different setting of the slider 42 on the slidewire 40 will produce a magnetic field of different strength surrounding the coil 34, thereby introducing a different viscosity in the fluid 10. Since the viscosity of the fluid is that which determines the time-delay, the change in the setting of the calibrated slidewire produces a corresponding change in the time-delay between the energization of the coil 30 and the closing of the circuit connected to the contacts 24 and 26.

In Figs. 2 and3 there is shown a somewhat diflerent structure which also embodies the present invention. In that structure there is illustrated a base member'which includes a non-magnetic member 46 defining the reservoir 48 for a quantity of viscous fluid 50 which, as before, exhibits the magnetic properties previously described. The base member also includes a pair of magnetizable polar members 52. These polar members serve to couple the fluid in the reservoir to the magnetic influence of an energizing coil 54. This energizing coil 54 surrounds a core member 56 which bridges the space between the two pole members 52.

Secured to the base member, as by a pair of rivets or screws 58, there is a non-magnetic spring member 60. This spring member 60 performs two functions. First it supports, in a position above the base member, a movable magnetic member 62. This magnetic member constitutes the movable core member of a solenoid, the field-coil 64 of which is supported on a non-magnetic pedestal member 66 which, in turn, rests upon or is secured to the base member. The second function of the spring member 60 is to carry a movable contact member 68 which may be moved between a first fixed contact member 70 and a second fixed contact member 72 by the operation of the solenoid.

Depending from the movable core 62 is a non-magnetic cylindrical member 74 which extends downward into the reservoir 48 engaging the fluid 50. The member 74 is hollow and is provided with an orifice 76 in the lower end thereof through which the fluid 50 may pass. Suitable means such as an O-ring 78 may be employed for retaining the fluid in the reservoir.

As may be seen in the drawings, the energizing coil 54 which is used to control the viscosity of the fluid 50 in the reservoir 48 lies along an axis which is transverse to the axis of the solenoid 64. This arrangement together with the spacing provided by the pedestal 66 tends to reduce to a minimum any interaction between the two field-coils.

In the operation of this structure, as in the structure illustrated in Fig. 1, the core member 62 is held in normal or de-energized position by the operation of the spring member 60. In this condition the contact member 68 may be closed on the first fixed contact 70. When, however, the solenoid coil 64 is energized the core member 62 will be urged downwardly. However, the downward motion of the core member together with its associated elements will be retarded or impeded by the viscous fluid in the reservoir 48. The rapidity of the downward motion of the core member 62 will be determined by the viscosity of the fluid 50 passing through the orifice 76 in the member 74. Here again, the viscosity of the fluid may be controlled by the application of a magnetic field from the core 54 to the fluid. After a period of time determined by the viscosity of the fluid, the core member 62 will be moved sufl'lciently to cause the contact member 68 to close on the fixed contact 72 thus providing a controlled time-delay between the initiation of the energizing signal and the closing of the circuit involving the contact 72.

Thus, it may be seen that there has been provided, in accordance with the present invention, an improved timedelay device which features a readily available variable time-delay means and which is simple in structure and operation.

What is claimed is:

A variable time-delay device comprising a solenoid driving means including a movable core member and an electrical field-coil, means for applying an energizing signal to said field-coil for imparting motion to said movable core member, switch means coupled to said core member for actuation thereby, viscous fluid damping means for retarding the motion of said core member, said damping means including a base member embracing a reservoir for a quantity of viscous fluid having a variable viscosity in response to variations in applied magnetic fields, non-magnetic means extending from said core member into said reservoir for engagement with said fluid, said nonmagnetic means having an orifice therein through which said fluid passes, said base including a second field-coil oriented transversely with respect to said first mentioned field-coil and pole piece means cou pling said second field-coil with said fluid in said reservoir, and means for selectively energizing said second field-coil to vary the viscosity of said fluid, whereby to selectively vary the time delay.

References Cited in the file of this patent UNITED STATES PATENTS 1,088,268 Fagerlund Feb. 24, 1914 1,288,017 Johnson Dec. 17, 1918 2,456,463 Starie a Dec. 14, 1948' 2,500,953 Libman d. Mar. 21, 1950 FOREIGN PATENTS 589,722 France Feb. 27, 1925 678,442 Great Britain Sept. 3, 1952 

